Search Results (149)

The interaction between the gut microbiota and human health has gained increasing recognition, accelerating advances in microbiome research. While early studies have emphasized probiotics, concerns regarding antibiotic resistance and adverse effects, such as sepsis, have shifted research interest towards heat-treated microbial cells or postbiotics. This study investigated the therapeutic potential of heat-killed postbiotic Enterococcus faecalis EF-2001—one of the most widely used postbiotics worldwide—for the prevention and treatment of muscle atrophy. In vitro, mouse C2C12 myotubes were pretreated with heat-killed postbiotic EF-2001 (50–500 μg/mL) for 48 h and then treated with dexamethasone (100 μM) to induce muscle atrophy. In vivo, male Sprague Dawley rats were treated with low-dose (3 mg/kg) and high-dose (30 mg/kg) EF-2001 for efficacy studies. Heat-killed postbiotic EF-2001 attenuated cellular and DNA damage in dexamethasone-induced C2C12 myotubes. Specifically, heat-killed postbiotic EF-2001 increased AKT phosphorylation while suppressing Atrogin-1 expression, thereby alleviating muscle atrophy. In a Sprague Dawley rat model, heat-killed postbiotic EF-2001 significantly reduced dexamethasone-induced muscle loss by regulating muscle atrophy-associated signaling pathways, including Atrogin-1 expression. Collectively, these findings demonstrate that heat-killed EF-2001 alleviates dexamethasone-induced muscle atrophy and support its potential as a postbiotic. This study provides a solid foundation for future human clinical studies by establishing preclinical evidence for the biological activity of heat-killed EF-2001. Full article

Secreted frizzled-related protein 3 (sFRP3/FRZB) is a soluble Wnt antagonist with established roles in skeletal development, however, its specific function in myogenesis remains underexplored. This study investigated the regulatory role of FRZB in muscle development, hypothesizing that it contributes to breed-specific growth differences in pigs. We examined FRZB expression in fetal tissues of slow-growing (Tibetan and Wujin) and fast-growing (Large White) pigs, and assessed its function in C2C12 myoblasts via siRNA-mediated knockdown. FRZB was widely expressed across porcine fetal tissues, with significantly higher abundance in the longissimus dorsi of slow-growing breeds. In vitro, FRZB silencing significantly enhanced myoblast proliferation and migration. Furthermore, knockdown accelerated differentiation and promoted the formation of longer, thicker multinucleated myotubes, accompanied by the upregulation of myogenic (MyoD, MyoG, MyHC) and fusion (β1-integrin, Myomaker) markers. Transcriptional profiling revealed a shift toward hypertrophy (Fst and Nog upregulation) and away from atrophy (Atrogin1 downregulation). These findings identify FRZB as a negative regulator of myogenesis via the Wnt signaling pathway. The elevated expression in indigenous breeds suggests FRZB may impose a molecular constraint on muscle development, highlighting its potential as a candidate gene for regulating carcass traits. Full article

Sarcopenia, an age-related muscle atrophy disease, is a major health concern in aging societies and is closely associated with severe chronic diseases. Its primary pathogenesis involves oxidative stress-induced apoptosis in muscle cells and an imbalance in protein metabolism. This study evaluated the potential of Rhododendron mucronulatum branch extract (RMB) and its major flavonoids, taxifolin-3-O-arabinopyranoside (Tax-G) and taxifolin (Tax-A), as natural therapeutic agents for sarcopenia. Phytochemical analyses were performed using TLC, HPLC, LC-MS/MS, and NMR, and Tax-G and Tax-A were isolated from RMB. In vitro models of apoptosis and muscle atrophy were established in C2C12 cells using H₂O₂ and dexamethasone (DEX), respectively. Cell viability, myotube diameter, and protein expression related to apoptosis and muscle differentiation were assessed. All three substances reduced H₂O₂-induced apoptosis by increasing Bcl-2 and inhibiting cleaved caspase-3 and PARP. They also attenuated DEX-induced muscle atrophy by suppressing Atrogin-1, MuRF1, and FoxO3α while promoting MyoD, Myogenin, Akt, and mTOR. Although Tax-A showed the highest activity, Tax-G exhibited comparable effects with lower cytotoxicity. These findings demonstrate that RMB and its active compounds protect muscle cells by regulating apoptosis and muscle metabolism, suggesting their potential as safe and functional natural materials for the prevention of sarcopenia. Full article

Cancer cachexia (CC) is a multifactorial, multi-organ syndrome characterized by systemic inflammation, metabolic dysregulation, anorexia, and progressive depletion of skeletal muscle and adipose tissue. Despite its high prevalence among patients with advanced malignancies, effective therapeutic options remain limited. Recent studies have elucidated the molecular underpinnings of CC and the therapeutic potential of natural herbs, highlighting the involvement of central nervous system regulation, adipose tissue, immune responses, gut microbiota, skeletal muscle, and disruptions in anabolic–catabolic signaling pathways such as mTOR, UPS, NF-κB, and STAT3. Persistent inflammation induces E3 ubiquitin ligases (Atrogin-1/MuRF-1) through cytokines including IL-6 and TNF-α, thereby impairing muscle homeostasis, while suppression of anabolic cascades such as IGF-1/mTOR further aggravates muscle atrophy. The limited efficacy and adverse effects of synthetic agents like megestrol acetate underscore the value of herbal therapies as safer adjunctive strategies. Botanicals such as Coicis Semen, Scutellaria baicalensis, and Astragalus demonstrate anti-inflammatory and muscle-preserving activities by modulating NF-κB, IL-6, and oxidative stress signaling. Numerous investigations indicate that these herbs downregulate MuRF-1 and Atrogin-1 expression, enhance appetite, and attenuate muscle loss, though they exhibit minimal influence on tumor suppression. While promising, current evidence remains largely preclinical and mechanistic validation is incomplete. This review consolidates contemporary insights into CC pathogenesis and the bioactivity of herbal interventions, highlighting the need for translational research to bridge preclinical findings with clinical applicability. Full article

Decreased skeletal muscle mass and function are a serious complication of long-term diabetes, often leading to numerous adverse outcomes. The primary pathological features of diabetic sarcopenia include muscle fiber atrophy and interstitial fibrosis. Although resistance exercise (RE) has been reported to mitigate skeletal muscle atrophy in type 2 diabetes mellitus (T2DM), the underlying mechanisms remain unclear. Fibroblast growth factor 21 (FGF21), an exercise-induced cytokine, has been shown to protect against skeletal muscle atrophy at elevated levels. In this study, a T2DM mouse model was established through 12 weeks of high-fat diet feeding and intraperitoneal injection of streptozotocin (STZ) to investigate the effect and mechanism of RE on skeletal muscle atrophy in T2DM mice. Our results demonstrated that 8 weeks of RE significantly decreased body weight, fat mass, triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), fasting blood glucose (FBG), and serum insulin levels in T2DM mice. RE also improved lean mass, glucose tolerance (IPGTT), and insulin tolerance (ITT). Additionally, RE increased skeletal muscle mass cross-sectional area (CSA) while attenuating fibrosis and inflammatory responses in skeletal muscle. Notably, RE upregulated FGF21 expression and activated the PI3K/Akt signaling pathway in diabetic skeletal muscle. RE promoted the phosphorylation of mTOR, 4EBP1, and p70S6K while suppressing the expression of the atrophy-related E3 ubiquitin ligases MuRF1 and MAFbx/Atrogin-1. Furthermore, RE inhibited lipid synthesis and enhanced both lipid oxidation and glucose utilization in skeletal muscle of T2DM mice. RE also improved mitochondrial biogenesis and dynamics in skeletal muscle of T2DM mice. In summary, 8 weeks of RE alleviated skeletal muscle atrophy in T2DM mice via activation of the FGF21/PI3K/Akt signaling pathway, which enhanced protein synthesis, improved glycolipid metabolism and mitochondrial quality control, and attenuated fibrosis and inflammation. Full article

Background: Obesity-associated skeletal muscle atrophy is characterized by reduced muscle mass with excessive adipose accumulation, and there is no approved pharmacological therapy targeting both muscle anabolism and lipid metabolism. The root part of Ophiopogon japonicus (OJ), an edible traditional medicine (Liriopis seu Ophiopogonis Tuber), exhibits anti-diabetic, anti-inflammatory, and cardioprotective properties, yet its impact on obesity-associated muscle atrophy remains unknown. Methods: This study investigated the therapeutic potential and mechanisms of OJ extract against muscle atrophy in high-fat diet (HFD)-induced obesity mice and palmitate (PA)-stimulated C2C12 myotubes. Results: In obese mice, the administration of OJ extract inhibited muscle loss, improved muscle strength, and attenuated hepatic steatosis and dyslipidemia. Furthermore, OJ treatment restored myotube diameter, increased the expression of MyHC and Myogenin, and suppressed the expression of Atrogin-1 and MuRF1 in C2C12 myotubes. At the molecular level, OJ extract activated the PI3K-AKT-mTOR/FoxO3a signaling pathway and reprogrammed lipid metabolism in gastrocnemius tissues and myotubes. Conclusions: OJ extract alleviates obesity-induced muscle atrophy through regulation of the PI3K-AKT-mTOR/FoxO3a signaling pathway and lipid metabolism in muscle, indicating its potential as a natural therapeutic agent for obesity-associated muscle atrophy. Full article

Sarcopenia, characterized by the progressive loss of skeletal muscle mass and function, is exacerbated by glucocorticoid exposure. Although there is growing interest in natural therapies for muscle atrophy, the effects of Quercus acuta Thunb. fruit extract (QA) on sarcopenia or glucocorticoid-induced muscle loss had not been previously investigated. QA is an evergreen oak known for its antioxidant and anti-inflammatory properties, with polyphenolic components reported to enhance oxidative and metabolic homeostasis in various tissues. Based on these properties, we hypothesized that QA could counteract muscle atrophy by modulating anabolic and catabolic signaling pathways. The research utilized both in vitro (C2C12 myotubes) and in vivo (ICR mice) models to assess QA’s effects. Daily oral administration of QA (100–200 mg/kg) was given to mice with dexamethasone (Dex)-induced muscle atrophy. Techniques included H&E staining to assess muscle mass and fiber cross-sectional area (CSA), Western blot, and ELISA analyses to investigate signaling pathways. Confocal imaging was also used to confirm cellular changes. In vitro QA treatment improved myotube integrity by increasing myogenic differentiation markers (MyoD, MyoG) and suppressing atrophy-related E3 ligases, specifically MuRF-1 and FBX32/Atrogin-1. Confocal imaging showed that QA inhibited the nuclear localization of FOXO1 and reduced FBX32 expression. In vivo, daily oral administration of QA significantly preserved gastrocnemius muscle mass and fiber cross-sectional area in Dex-treated mice. QA restored the IGF-1/PI3K/Akt signaling pathway and attenuated FOXO1-dependent proteolytic activation. Collectively, these findings demonstrate that QA possesses potent anti-atrophic and myoprotective effects mediated through the modulation of the IGF-1/Akt-FOXO axis. QA has potential as a novel natural therapeutic for preventing glucocorticoid-induced sarcopenia. Full article

Type 1 diabetes mellitus is a major risk factor for both sarcopenia and osteoporosis, primarily due to the body’s inability to utilize glucose as a result of insulin deficiency. Impairments in insulin and glucose signaling can accelerate the decline in muscle and bone health. To investigate this interaction, we examined whether insulin deficiency exacerbates muscle and bone deterioration in Chrebp knockout (KO) mice. Male wild-type (WT) and KO mice, aged 18 weeks, were intraperitoneally treated with 200 mg/kg BW streptozotocin (STZ), which selectively destroys pancreatic beta cells, thereby inducing insulin deficiency. Two weeks after STZ administration, compared with STZ-treated WT mice, STZ-treated KO mice presented significantly greater reductions in body weight and gastrocnemius muscle weight (BW: WT-vehicle vs. WT-STZ; 2.58 [−1.23, 6.39] (p = 0.21); KO-vehicle vs. KO-STZ: 8.03 [5.23, 10.82]; GA muscle: WT vehicle vs. WT STZ: 0.084 [0.047, 0.12], p < 0.0001; KO vehicle vs. KO STZ: 0.084, [0.047, 0.12], p < 0.0001). The decrease in grip strength caused by STZ administration was greater in the KO mice than in the WT mice (mean differences [95% CIs]: WT vehicle—WT STZ, 49.6. [0.9, 98.4], p = 0.046; WT STZ—KO STZ: 71.40 [29.1, 113.7], p = 0.0059; KO vehicle—KO STZ: 84.3 [51.9, 116.8], p = 0.0003). Consistent with these findings, STZ administration reduced IGF-1 expression and increased atrogin mRNA levels, with the highest levels in STZ-treated KO mice. In skeletal muscle, the changes in IGF-1 and Atrogen induced by STZ administration were significantly greater in the KO group than in the WT group (IGF-1: WT vehicle—WT STZ: 0.19 [−0.072, 0.46], p = 0.17; KO vehicle—KO STZ: 0.79 [0.53, 1.06], p < 0.0001; Atrogen: WT vehicle—WT STZ: −2.7 [−3.01, −2.29], p < 0.0001; KO vehicle—KO STZ: −3.35 [−3.71, −2.99], p < 0.0001). The BMD in the Chrebp-deficient group was greater than that in the wild-type group (WT vehicle—KO vehicle: −5.2 [−8.4, −1.9], p = 0.0014); however, the administration of STZ significantly decreased the BMD only in the KO group (WT vehicle—WT STZ: p = 0.45, KO vehicle—KO STZ: 7.2 [3.9, 10.4], p < 0.0001). These results suggest that Chrebp deficiency combined with insulin deficiency aggravates sarcopenia and osteoporosis risk. Therefore, insulin and glucose signals are important for maintaining muscle and bone mass and function. However, further studies are needed to elucidate the mechanisms by which ChREBP deletion and insulin deficiency cause osteosarcopenia. Full article

Background: Sarcopenic obesity (SO) and diabetic sarcopenia (DS) represent overlapping metabolic–musculoskeletal disorders characterized by the coexistence of excessive adiposity, insulin resistance, and progressive muscle wasting. The Planetary Health Diet (PHD), proposed by the EAT–Lancet Commission, emphasizes plant-forward, nutrient-dense, and environmentally sustainable food patterns that may concurrently address metabolic and muscle health. This review aimed to systematically evaluate dietary and bioactive nutritional interventions aligned with the PHD and their effects on muscle mass, strength, metabolism, and underlying mechanisms in SO and DS. Methods: Following PRISMA guidelines, studies published between 2015 and 2025 were identified across PubMed, Scopus, and Google Scholar. Eligible studies included dietary, nutritional, or supplement-based interventions reporting muscle-related outcomes in obesity- or diabetes-associated conditions. Results: Ninety-one eligible studies were categorized into plant-derived, animal/marine-based, microorganism/fermented, synthetic/pharmaceutical, and environmental interventions. Across diverse models, bioactive compounds such as D-pinitol, umbelliferone, resveratrol, GABA, ginseng, whey peptides, probiotics, and omega-3 fatty acids consistently improved muscle mass, strength, and mitochondrial function via AMPK–SIRT1–PGC-1α and Akt–mTOR signaling. These mechanisms promoted mitochondrial biogenesis, suppressed proteolysis (MuRF1, Atrogin-1), and enhanced insulin sensitivity, antioxidant capacity, and gut–muscle communication. Conclusions: PHD-aligned foods combining plant proteins, polyphenols, and fermented products strengthen nutrient sensing, mitochondrial efficiency, and cellular resilience, representing a sustainable nutritional framework for preventing and managing SO and DS. Full article

Background/Objectives: Premature births below 32 weeks of gestation generally require respiratory oxygen support, leading to a relatively hyperoxic environment compared to in utero conditions. Transient hyperoxia exposure has been linked to an elevated risk of chronic lung disease and retinopathy of prematurity; however, its effects on skeletal muscles remain elusive. This study aimed to investigate the effects of hyperoxic exposure in rats as a model of premature infants receiving supplemental oxygen (30–60% O₂ for several weeks). We hypothesized that rats exposed to postnatal hyperoxia would exhibit muscle fiber atrophy and alterations in fiber type. Methods: We used a rat model in which newborns were exposed to 80% oxygen from birth until postnatal day 12. We assessed the gastrocnemius muscles of rat legs at 12 weeks. Results: Rats exposed to hyperoxia showed substantially increased protein expression of Atrogin-1, along with elevated levels of adipophilin, myogenic differentiation factor 1, and myogenin. No significant changes were observed in the expression of slow or fast myosin heavy chain proteins. However, myofiber size in the gastrocnemius muscle was reduced in the hyperoxia-exposed group compared to the control group. Conclusions: Thus, transient hyperoxia exposure during early life can impede skeletal muscle development, potentially extending into adulthood. Full article

Background and Objectives: Cancer cachexia is a debilitating metabolic syndrome highly prevalent in colorectal cancer (CRC), characterized by progressive skeletal muscle wasting. The myostatin–FOXO signaling pathway contributes to this process by activating the E3 ubiquitin ligases MuRF-1 and Atrogin-1. Exercise is a promising non-pharmacological strategy, but its effects on this pathway in CRC cachexia remain unclear. This review aimed to synthesize preclinical evidence on the impact of exercise on the myostatin–FOXO axis. Materials and Methods: A comprehensive search was performed in PubMed/MEDLINE, Scopus, Web of Science, and Science Direct from inception through August 2025. Eligible studies included murine CRC models (C26 or Apc^Min/+) exposed to aerobic, resistance, or combined exercise interventions, with outcomes assessing myostatin, FOXO, MuRF-1, or Atrogin-1. Study quality was appraised using the CAMARADES 10-item checklist. Results: eleven studies met the criteria, with quality scores ranging from 6 to 8. Aerobic exercise, particularly voluntary wheel running, most consistently reduced MuRF-1 expression and systemic inflammation, whereas resistance and eccentric training exerted stronger inhibitory effects on FOXO and Atrogin-1. Myostatin was directly measured in two studies, yielding inconsistent results. Resistance and eccentric training promoted anabolic signaling (e.g., mTORC1), whereas aerobic protocols improved oxidative capacity. Variability in exercise type, intensity, and duration contributed to heterogeneity across findings. Conclusions: Exercise attenuates skeletal muscle catabolism in CRC-induced cachexia, mainly through modulation of the myostatin–FOXO pathway and downstream ligases. However, limited direct data on myostatin and methodological heterogeneity underscore the need for standardized protocols and translational studies. This review provides the first focused synthesis of exercise-mediated regulation of this pathway in CRC cachexia. Full article

The C9ORF72 gene mutation is a major cause of amyotrophic lateral sclerosis (ALS). Disease mechanisms involve both loss of C9ORF72 protein function and toxic effects from hexanucleotide repeat expansions. Although its role in neurons and the immune system is well studied, the impact of C9ORF72 deficiency on skeletal muscle is not yet well understood, despite muscle involvement being a key feature in ALS pathology linked to this mutation. This study examined skeletal muscle from C9ORF72 knockout mice and found a 19.5% reduction in large muscle fibers and altered fiber composition. Ultrastructural analysis revealed mitochondrial abnormalities, including smaller size, pale matrix, and disorganized cristae. Molecular assessments showed increased expression of Atrogin-1, indicating elevated proteasomal degradation, and markers of enhanced autophagy, such as elevated LC3BII/LC3BI ratio, Beclin-1, and reduced p62. Mitochondrial quality control was impaired, with a 3.6-fold increase in PINK1, upregulation of TOM20, reduced Parkin, and decreased PGC-1α, suggesting disrupted mitophagy and mitochondrial biogenesis. These changes led to the accumulation of damaged mitochondria. Overall, the study demonstrates that C9ORF72 is critical for maintaining muscle protein and mitochondrial homeostasis. While C9orf72-haploinsufficiency does not directly compromise muscle strength in mice, it may increase the vulnerability of skeletal muscle in C9ORF72-associated ALS. Full article

Long-term spaceflight induces multisystem stress, including cardiovascular deconditioning, skeletal muscle atrophy, immune suppression, and neuro-ocular syndromes. Current countermeasures reduce symptoms but cannot replicate the synergistic resilience needed for extended missions or critical illness. Hibernating animals, specifically brown bears (Ursus arctos), survive prolonged immobility, starvation, and bradycardia without resultant pathology. This review incorporates adaptations observed in bears and certain torpid species, including reversible insulin resistance, suppression of muscle atrophy genes MuRF1 and Atrogin-1, and maintenance of the heart despite seasonal production decline. The thirteen-lined ground squirrels (Ictidomys tridecemlineatus) maintain retinal structure and synaptic stability throughout torpor, avoiding neuro-ocular complications despite prolonged inactivity. Mechanisms span from RBM3-dependent synaptic maintenance, titin isoform remodeling under the control of RBM20, mTOR and FOXO pathway regulation, remodeled hydrogen sulfide metabolism, and microbiome-mediated nitrogen salvage. These adaptations are different from human adaptation to microgravity and disuse and offer translational candidates for synthetic torpor, probiotic engineering, neuroprotection, and protein-sparing therapy. Hibernators are not passive stress subjects; they perform coordinated anticipatory responses in multiple organs. Comparing these systems in large and small hibernators, we aim to uncover a biologically realistic path to human resilience. These findings guide a shift from reactive, pharmacological measures for preserving human health during space flight, intensive care, and extreme environments towards proactive, biologically initiated measures. Full article

Pediatric type 1 diabetes (T1D) disrupts musculoskeletal development during critical windows of growth, puberty, and peak bone mass accrual. Beyond classic micro- and macrovascular complications, accumulating evidence shows a dual burden of diabetic bone disease—reduced bone mineral density, microarchitectural deterioration, and higher fracture risk—and diabetic myopathy, characterized by loss of muscle mass, diminished strength, and metabolic dysfunction. Mechanistically, chronic hyperglycemia, absolute or functional insulin deficiency, and glycemic variability converge to suppress PI3K–AKT–mTOR signaling, activate FoxO-driven atrogenes (atrogin-1, MuRF1), and impair satellite-cell biology; advanced glycation end-products (AGEs) and RAGE signaling stiffen extracellular matrix and promote low-grade inflammation (IL-6, TNF-α/IKK/NF-κB), while oxidative stress and mitochondrial dysfunction further compromise the bone–muscle unit. In vitro, ex vivo, and human studies consistently link these pathways to lower BMD and trabecular/cortical quality, reduced muscle performance, and increased fractures—associations magnified by poor metabolic control and longer disease duration. Prevention prioritizes tight, stable glycemia, daily physical activity with weight-bearing and progressive resistance training, and optimized nutrition (adequate protein, calcium, vitamin D). Treatment is individualized: supervised exercise-based rehabilitation (including neuromuscular and flexibility training) is the cornerstone of skeletal muscle health. This review provides a comprehensive analysis of the mechanisms underlying the impact of type 1 diabetes on musculoskeletal system. It critically appraises evidence from in vitro studies, animal models, and clinical research in children, it also explores the effects of prevention and treatment. Full article

Muscle atrophy is defined as reductions in muscle size and function and represents a critical concern affecting elderly populations, immobilized patients, and individuals following specific dietary regimens, such as fasting and low-protein diets. This study investigated the protective effects of Stellaria dichotoma root extract and its isolated bioactive compounds during muscle atrophy using both in vitro and in vivo experimental models. First, S. dichotoma root extract prevented dexamethasone (DEX)-induced atrophy in C2C12 myotubes. Through systematic solvent partitioning and resin chromatography, five compounds (1–5) were successfully isolated from the n-butanol fraction. Dichotomine B (2) was identified as the most abundant and bioactive constituent. Treatment with dichotomine B significantly preserved the myotube diameter, enhanced the fusion index, and maintained the myosin heavy chain protein level while suppressing key atrophic biomarkers, including FoxO3a, MuRF-1, and Atrogin-1, in DEX-treated myotubes. Furthermore, dichotomine B (2) reduced proteolysis in serum-free cultured C2C12 myotubes and in mice subjected to 48 h of fasting, preserving muscle mass and strength. These findings suggest that S. dichotoma root extract and its principal compound, dichotomine B (2), have promising therapeutic potential and provide an opportunity to develop novel pharmacological interventions against muscle wasting through suppression of proteolysis pathways. Full article